Elisabetta Grillo, 41, said she found various signs that Lawson was using cocaine, including a packet of white powder found in a toilet in the home she shared with former husband, John Diamond, as well as rolled-up banknotes and credit cards with white powder on them.
Asked if she had ever seen the TV cook taking drugs, Grillo — who is also known as Lisa — said “No”.
But she told Isleworth Crown Court in west London that she was aware that Lawson had taken drugs and, when pressed by barrister Anthony Metzer QC about what type of substances, she said both cocaine and cannabis.
Grillo, who worked for Lawson as an au pair, said she did not confront the 53-year-old about the issue as she did not want to embarrass her.
Italian-born Grillo, who is accused alongside her sister, Francesca, of defrauding Lawson and Saatchi, said that, when she was living with Lawson in Shepherd’s Bush around a year after she first started working for her and then-husband John Diamond, she found a small packet of white powder in the toilet while cleaning.
She told the court: “I was cleaning the house and I noticed a little packet on top of the loo, toilet. I opened it because it was kind of a little funny envelope and I saw white powder.”
On other occasions she said she found rolled-up notes — on one occasion a £20 note — with white powder on them.
” Once I noticed a credit card with white, and a CD, like a music CD, with white stuff,” she said.
Grillo also told the court she found similar evidence when Lawson moved in with Saatchi at his home in Eaton Square.
She said that in a drawer in Lawson’s office she found rolled-up banknotes, including American dollars.
Asked by Mr Metzer if there was anything on them, she said: ” Yes, again, white stuff.”
The defence barrister asked her how often over the years she had seen signs of drug use, to which she replied: “Regularly.”
The celebrity cook last week admitted taking cocaine with Diamond when he found out he had terminal cancer, and on another occasion in Jul 2010 during her troubled marriage to Saatchi.
But Lawson, who also admitted smoking cannabis in the last year of her marriage to the art gallery owner, said the idea that she was a drug addict or habitual user of cocaine was “absolutely ridiculous” and accused her ex-husband of “peddling” stories about her alleged habit.